Method for fastening an attachment or suspension device and a device for carrying out the method

ABSTRACT

A method for fastening an attachment or suspension device to a porous support surface, preferably plasterboard, and also a device for carrying out the method. The device is secured to the support surface by means of fastener means, which preferably have a V-like configuration, the legs of which are driven through through-passing holes in the device attachment part. The holes have provided therein specially formed device parts which, when the fastener means is driven into the support surface, are operative in causing the legs of the fastener means to progressively diverge further within the support surface, such as to create force-absorbing crushed zones in abutment with the fastener legs.

TECHNICAL FIELD

A method for fastening an attachment or suspension device to a poroussupport surface, preferably a plasterboard support surface, and anattachment device for carrying out the method.

BACKGROUND PRIOR ART

Because present day building materials are required to be resistant toboth fire and mold, woodfiber board and chipboard is being replaced toan ever increasing extent with primarily plasterboard (gypsum).

Several methods and devices for fastening electric cables, paintingsetc., to porous support surfaces, such as plasterboard panels, or forsuspending devices on such surfaces are known to the art. Those methodswhich afford the most reliable attachment are based on the use ofattachment devices comprising fasteners which pass through the panels,or on the use of special duty plaster screws or plugs. One drawback withsuch attachment devices is that they are difficult and time consuming toattach. Furthermore, such devices are relatively expensive. The quickestway of securing articles to such porous support surfaces is to use,inter alia, conventional attachment and suspension devices, such as nailclamps and X-hooks. Although these attachment devices are able to takeup transversely acting loads in an acceptable manner, they are less thansatisfactory with regard to taking up loads which act in afastener-withdrawing direction. In order to obtain reliable attachmentto the best possible extent when using attachment devices of this kind,it is desirable to locate the attachment devices in positions in whichthe fasteners used therewith will enter into an underlying stud ornogging-piece. When the articles to be attached in this way are electriccables, it is found necessary in some cases to extend the cables fartherthan would otherwise be required and, moreover, often in a manner whichis less pleasing from an aesthetic point of view.

In order to enhance the ability of conventional attachment andsuspension devices to take up such fastener-withdrawing forcessatisfactorily, it has been proposed to skew-nail such devices to thesupport material, skew-nailing being a method in which nails are driveninto the support material while inclined thereto. When skew-nailing,there has been used either two separate nails or a U-shaped fastenerwhose legs are caused to diverge or converge through the action ofguides provided in the attachment device and/or are formed at theirextremities in a manner which will ensure that the legs converge ordiverge when driven into said support material. Both of these variantsare disclosed in the German Offenlegungsschrift No. DE 3115914 A1, forexample FIG. 9 of this publication illustrates an attachment devicewhich is secured with the aid of two nails, whereas FIGS. 3 and 5 of thepublication illustrate an attachment device which is fastened with theaid of a U-shaped fastener, this fastener being shown separately in FIG.6.

Both of these fastener types have the drawback of relaxing their gripslightly when subjected to relatively small withdrawing forces, suchthat the attaching device will no longer abut the support surface. Thisis due to the fact that the bearing surface of the fastener means whichtakes up the withdrawing forces is relatively small in area, andconsequently the surface pressure thereon becomes so high as to crushthe underlying brittle support material. As the attachment device moves,this crushed material becomes packed forwardly of the fastener means inthe withdrawing direction thereof and forms cushions or crushed-zoneswhich are able to withstand the withdrawing forces to a greater extentthan the unaffected material and therewith prevent continued withdrawalof the fastener means used to fasten the attachment device. When thesewithdrawing forces cease, the attachment device will return, eitherpartially or fully, to its original position. Furthermore, the crushedmaterial in the fastener holes of the attachment device is oftenredistributed so that upon the reoccurrence of such withdrawing forcesfurther material is crushed. Should these withdrawing forces be repeatedintermittently, the fastener means will gradually work out of thesupport surface and the attachment will become progressively looser,until it falls away. These intermittently occurring forces which tend towithdraw the fasteners may be caused as a result of cleaning or dustingexternally fitted cables of various kinds, for example. When theattachment device is used to hang paintings, pictures, or mirrors in thevicinity of doors, such withdrawing forces may occur intermittently as aresult of closing the door. For example, the surges of air generatedwhen closing the door are liable to cause the painting, etc., to rockand thereby subject the fasteners to withdrawing forces.

SUMMARY OF THE INVENTION

The object of the invention is to provide a method and a device thereforwhich will overcome the aforedescribed difficulties. This object isachieved with the aid of fastener means which are so formed that whenapplied they are caused to expand within the support surface, such as tocreate crushed zones which improve the ability of the fastener means totake-up load.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which FIG. 1 is a sectional view of anattachment device and co-acting fastener means, shown in various whensecuring the device to a support surface; FIG. 2 illustrates inperspective an embodiment which has the form of a cable clip withassociated V-shaped fastener means; FIG. 3 is a plan view of a furtherembodiment, in the form of an attachment device provided with a hook;FIG. 4 is a bottom plan view of a three-legged fastener means; and FIG.5 illustrates in side view and partially in section the suspensiondevice of FIG. 3 in cooperation with the fastener means of FIG. 4.

Detailed Description of Preferred Embodiments According to the Invention

FIG. 1 illustrates in section an attachment or suspension device whichis preferably made of a plastics material and which co-acts with aV-shaped fastener means 2, the fastener means being shown in its variousstages when securing the attachment device to a support surface 3. Forspace reasons, FIG. 1 has been divided into two halves, which have beendisplaced relative to one another. The left-hand part of FIG. 1 shows,in full lines, the V-shaped fastener means 2 positioned in theattachment device 1 prior to driving the fastener means into the supportsurface 3, which may comprise plasterboard or like material. Thefastener means is made from a hard material, preferably steel, whosehardness has been further enhanced by cold working when bending thefastener means to its V-shape. The distance between the points of thelegs of the fastener means 2 is adapted to the length of the base of atrapezoidal shaped part 4 incorporated in the attachment device 1, saidtrapezoidal shaped part 4 being intended to cause the fastener legs todiverge progressively still further as the fastener means is driven intothe support surface. As the fastener legs diverge and the angletherebetween increases, the legs will enlarge or widen the holes causedby preceding leg parts during the entry of the legs into the supportsurface 3. The fastener is shown in dotted lines on intermediate stageof a fastener driving operation. The fasting is illustrated inchain-dotted lines fully driven into the support surface 3. Asillustrated in FIG. 1, the lateral movement executed by the fastenerlegs causes the holes 6 made by the legs to widen considerably. In thisway, the material located in the wall of each hole 6 is crushed in theaforesaid direction of lateral movement, to form a crushed zone 5 inwhich the material is packed together so as to create a cushion whichtransfers the laterally acting force from the fastener means 2 to thesupport surface 3 and spreads the force to a larger area around thefastener means and therewith produces the same effect as that whichwould be produced if the force take-up surface of the fastener means wasenlarged. When compared with a fastener means of the kind in which thefastener legs are replaced with nails which are of the same length anddiameter and which are skew-nailed into the support surface at anglescorresponding to fully driven-in legs, the force required to loosen theinventive attachment device and fastener means, i.e. the withdrawingforce, is several times greater.

The reference numeral FIG. 1 identifies the tip of the leg of a fastenermeans which has been driven fully into the support surface andillustrates the position which the fastener leg would have taken if theleg had not encountered a progressively increasing resistance from thecrushed zone during lateral movement of the leg as it is driven intosaid support surface. As a result of this resistance the part 4 of theattachment device is deformed to some extent and the fastener legundergoes a certain degree of elastic deformation and therefore becomespre-stressed, such as constantly to hold the crushed zone under pressureand therewith also to hold the attachment device 1 in close abutmentwith the support surface 3. This pressure is not found in the case ofdevices which are skew-nailed, which is the reason why the fastenermeans of such devices tend to "eat" their way out of the support surfacewhen subjected to intermittent loads, as beforementioned. Neither isthis effect obtained with known attachment devices of the kind which areintended to co-act with slender and relatively soft U-shaped fasteners,whose legs are guided in holes or grooves in the attachment device so asto enter the support surface at an inclined angle, corresponding toskew-nailing, or with which the end surfaces of the fastener legs areformed so as to produce a corresponding effect.

FIG. 2 is a perspective view of a cable clip 8 which is preferably madeof a plastic material and which is intended to be fastened to thesupport surface with the aid of V-shaped fastener 2. The clip includesan attachment part 9 which has an essentially flat undersurface forabutment with the support surface, and also an arm 10 which extends fromthe attachment part 9 and which is intended to grip around a cable orthe like to be attached to the support surface. The fastener 2 is placedin a rectangular, through-passing hole 11 which has located centrallytherein trapezoidal shaped part 4 which is arranged in the mannerillustrated in FIG. 1, such that the upper surface of said part islocated beneath the upper surface of the attachment part 9 to such anextent that when the fastener means 2 is brought into abutment with theupper surface of the part 4 as the fastener means is driven into thesupport surface, the upper edge of the fastener 2 will lie parallel withthe upper surface of the attachment part 9. These cable clips are suitedfor use with any kind of fastener applicator or nail driving pistol, theclips, in this case, preferably being produced in a long, continuousstrip. In this regard, the fastener means are placed in respective clipsprior to inserting the clips into the pistol magazine, or alternativelythe fastener means can be placed in a separate magazine and inserted inthe clips in conjunction with firing the clips from the applicator orpistol.

The V-shaped fastener means is preferably manufactured from spring steeland the fastener part joining the fastener legs preferably has a radiusof curvature which is equal to or smaller than the diameter of the wirefrom which the fastener means is made. The trapezoidal-shaped part 4 hasan upper surface which is essentially flat. When the fastener means isdriven into the support surface, and therewith into abutment with saidupper surface, the corners of the trapezoidal-shaped part aresubsequently deformed to some extent, therewith exerting a gentleretardation force to the fastener means.

FIG. 3 is a plan view and FIG. 5 a side view, partly in section, of anembodiment of the invention comprising a suspension device 12 whichincludes a circular attachment part 13 having a centrally locatedcircular hole 14, in which a hub 15 in the shape of a truncated cone isarranged with the base surface of the cone in the plane of the surfaceof the attachment part 13 intended for abutment with the support surfaceand connected to the defining wall of the hole by means of three spokes16, and which further includes an arm 17 which extends from theattachment part 13 and which is also intended for abutment with thesupport surface, the end part of the arm 17 merging with a hook 18. FIG.5 illustrates the suspension device 12 in co-action with a fastenermeans 19 which comprises a base part 20 having extending therefrom threelegs 21 which are placed in the openings located between respectivespokes 16 when fastening the suspension device 12 to a support surface3. When the fastener legs 21 are driven into the support surface 3, thelegs are caused to diverge within the confines of the support surface,such as to create crushed zones on mutually opposing sides of the legs21, in the manner aforedescribed. FIG. 4 is a bottom plan view of thefastener means 19, separate from the attachment device. The fastenermeans concerned is punched from sheet steel and the fastener legs arethen bent while simultaneously cold working or bossing the device.

The fastening reliability of the described suspension device andattachment device, and the method applied therewith, is greatly superiorto the fastening reliability of conventional methods and devices whenthe length of the fastener means is at least 2.5, preferably 3.5-4 timesthe height of the trapezioidal-shaped part, and when the angle definedby the fastener legs with the symmetry line of the attachment device isgreater than 8°, and if possible at least 11°. The length of thefastener means in relation to that part of the device which causes thedevice to expand in the support surface, and also the extent of suchdivergence, can be varied within relatively wide limits withoutdeparting from the scope of the invention.

What is claimed is:
 1. A fastening method comprising placing anattachment or suspension device on a porous support, the device having afastener projecting from the device and provided with diverging legsstraddling a tapered part, the legs having piercing ends abuttingagainst the surface of the porous support in a space around the taperedpart and driving the fastener inwardly into the porous surface whileconcurrently increasing progressively the angle of divergence of thelegs as the legs advance on said tapered part so that as said legsprogressively penetrate into the porous support the legs are caused toturn outwardly and widen the hole formed by the penetration of legs intothe porous support and laterally crush the material of the poroussupport.
 2. A method as claimed in claim 1 wherein initially the angleof divergence of the legs of the fastener is less than the angle oftaper of the tapered part, and after the fastener is driven completelyinwards the legs abut against and have an angle of divergence conformingto the tapered part, the angle at which the legs penetrate into theporous support progressively varying between the initial and finalangles.
 3. A method as claimed in claim 2 wherein the penetration of theends of the legs takes place with axial and turning movements to producea prestress in the fastener.
 4. An attachment or suspension device forbeing secured to a porous support comprising an attachment part having aflat surface for abutment against a porous support, said attachment partincluding a tapered part with an open region around said tapered part,and a fastener including two divergently inclined legs straddling saidtapered part and having piercing ends disposed in said open region inthe vicinity of said flat surface, said legs having an angle ofdivergence which is less than the angle of said tapered part, said openregion having a lateral extent greater than that of said legs andsufficient to permit the angle between the legs of the fastener toincrease as the legs penetrate into the porous support and enable thelegs concurrently to turn outwardly and progressively widen the holeformed by the penetration of the legs into the support and cause lateraloutward crushing of the material of the support.
 5. A device as claimedin claim 4 wherein said tapered part is trapezoidal and said fastener isV-shaped.
 6. A device as claimed in claim 4 wherein said tapered parthas an outer conical surface conical and said fastener has three legs.7. A device as claimed in claim 6 wherein said attachment part includesa radial arm, said open region being provided by three openings intowhich said three legs are respectively positioned, said fastenerincluding a base part from which said legs extend.
 8. A device asclaimed in claim 7 wherein said attachment part includes an annularportion surrounding said base part.
 9. A device as claimed in claim 4wherein said attachment part is made of plastic material and saidfastener is made of steel.
 10. An attachment or suspension device forbeing secured to a porous support comprising an attachment part having aflat surface for abutment against a porous support, said attachment parthaving a through opening therein, and a fastener projecting from saidattachment part and including two divergently inclined legs extendinginto said opening, and means in said attachment part bounded by saidthrough opening for causing said inclined legs of the fastener topenetrate into the porous support, when the fastener is driven into theattachment part, with an axial movement and a concurrent progressivelyoutward bending movement to produce lateral crushing of the material ofthe porous support.
 11. A device as claimed in claim 10 wherein saidmeans includes a tapered part and an opening means therearound, saidlegs of said fastener being engaged in said opening means.
 12. A deviceas claimed in claim 11 wherein said legs straddle said tapered part andhave piercing ends initially disposed at the level of the flat surfaceof the attachment part, said legs having an angle of divergence which isless than the angle of the tapered part.
 13. A device as claimed inclaim 10 wherein said attachment part is made of plastic material andsaid fastener is made of steel.